Hi
I've read some (Doc's) prior posts on this subject; just need a little verification that I'm on the right track.
I'm in the process of rewiring my project (39 Chevy small block, etc.). I've run a 1/0, 12VDC+ from Battery to starter.
Since the internally regulated 3-wire Alternator is on the same (Driver's) side of the car, my plan is to run the 10G. charge cct. directly to the Battery +(Cutoff) Post (rather than to the conventional Starter Post) I can better hide the wiring using this routing. Should be the same end result????? Or am I missing something?
As regarding the Alternator's Regulator Wire ------- just run a jumper from the Alternator's Batt post to it's "terminal 1" , or "R" terminal?
As for the rest of the wiring , I'm planning to run a 12g. purple wire from ignition switch, through the neutral safety switch, and on to the starter's "s" terminal. Right?
As far as I figure, there is only one (12g. Pink) wire that's runs directly from the Ignition Switch to the HEI. Yes?
If someone could confirm, or correct the above, I'd say "Thanx"
ARPEE

You can run the 10 gauge charge wire directly from the alternator post to the battery, but you need a 14 gauge fusible link (or a fuse) in the wire. Also take a look at this web site for some additional info on wiring a 10si or similar alternator.

Thanks Bruce.
I'll take your recommendation to install the fusible link (fuse) in the Alternator>Battery Post circuit.
I also viewed the website you suggested. It states that "Term 1" is wired in series with a warning lamp, and "Term 2" is another 12VDC+ circuit to "exite" the Alternator.
An American Autowire schematic I just found, shows running a jumper wire from the "BAT term" to "Term 2", and an exiter (12VDC) wire from the "ACC Term" on the Ignition Switch to "Term 1" on the Alternator.
Yet another website schematic shows supplying 12VDC to all three terminals, i.e. 10g wire from Battery Post to BAT terminal on Alternator, then running jumper wires from BAT to both Term 1 & 2.
I'm confused. Are all of these approaches really just different ways of achieving the same end result?

Terminal 1 is for a light on the dash, and is optional. In other words, the alternator will charge just fine whether you connect it or not. GM connected it to one side of a bulb, and the other side of the bulb connects to switched, fused battery power.

Terminal 2 is for "remote voltage sensing". GM ran a small gauge wire from this terminal to the main electrical junction block, not the back of the alternator.

Electrically and on paper, it all looks the same -- wiring Terminal 2 straight to the battery, back of alternator, or main electrical junction block should work, right? The alternator will charge when Terminal 2 is jumpered to the BAT terminal, and the wiring will look cleaner

- BUT -

and this is the big deal -

this simple connection really needs a small gauge wire run to that point where all your fusible links and/or fuses are tied together to the battery feed, which is the main electrical junction block.

Why? The voltage at the main electrical junction block is lower than at the back at the alternator: there is a voltage drop through the wire from battery to the main electrical junction block. On most GM cars that's a long wire and volt or more is lost in it.

The remote sense connection to the regulator tells the alternator to crank out enough volts to bring the main electrical junction block up to 13.8 volts or more, insuring all the accessories and ignition get proper voltage. Your car will have low system volts if you jumper Terminal 2 to the battery or alternator, so take the time and wire it all the way back to the main electrical junction block.

this simple connection really needs a small gauge wire run to that point where all your fusible links and/or fuses are tied together to the battery feed, which is the main electrical junction block.

Why? The voltage at the main electrical junction block is lower than at the back at the alternator: there is a voltage drop through the wire from battery to the main electrical junction block. On most GM cars that's a long wire and volt or more is lost in it.

The remote sense connection to the regulator tells the alternator to crank out enough volts to bring the main electrical junction block up to 13.8 volts or more, insuring all the accessories and ignition get proper voltage. Your car will have low system volts if you jumper Terminal 2 to the battery or alternator, so take the time and wire it all the way back to the main electrical junction block.

Jon P

So is this why I never read more than 12.4 in my car?? I thought it might be a weak alt. I have a Centech kit in mine, with the alt batt wire going to a junction buss-back to the batt. The batt wire and the exciter are tied together at the alt. Have a 6' piece of resistor wire going back to the fuse block.
The junction block is also the feed to the ignition switch and the fuse block.

With the engine fans and or the AC running voltage drops to about 11.6
But it seems everything is working okay(except the cd changer).

Pretty much all high loads originate from the battery thru a relay, so maybe the voltage readings I get inside the car---are not the same as the voltages under the hood?

I am curious about the piece of resistive wire you mention. Exactly what is that connected to on both ends?

Your low-volt condition is exactly the kind of problem I have fixed with a simple re-routing of the sense wire. On custom vehicles, and many of those have had really powerful aftermakrket alternators, I always connect the sense wire to the main distribution point for all the accessories. On a stock vehicle wiring harness this is usually a nut-and-bolt terminal in a block of plastic on the firewall... and in a custom this might be a relay or some other central wiring feed point in the bed of a truck, under the dash, or in the back seat area.

I have seen the voltage at the back of the alternator at 13.8 volts and at a junction block 14 feet of wire away at 11 volts. Running a sense wire to the that point raises the junction block to 13.8 volts - I have then seen the voltage at the back of the alternator at 15 or more, but the fans and radios and lights are now speedy, playing and bright.

My resistor wire is the brown (gen lamp) wire in Doc's post.
As I have digital gages the warning lamp is not used.
The resistance wire was supplied in place of a diode.
The man at Centech explained to me that approx. six feet of wire
was needed to prevent failure to shut motor down. It was also explained
that all cars did not have a tendancy to keep running after the key
was turned to the off position, but some did.
As I have had electric fans prevent my 79 c-10 from shutting off in the past,
it would be in my best interest to keep this wire.
It was also explained the wire stood in place of the lamp which is not used
on most rewiring projects.
So--The wire is fed from the fuse box (ignition buss i think) to the term on the
alt.
I guess that in the event of an alt failure--it would ground and illuminate the lamp. Resistance wire is between lamp and alt--(actually bulkhead connector on my car) and I think 14 ga GXL from the lamp to the fuse box.

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